The present invention relates to a motor vehicle braking apparatus using accelerator pedal arranged such that the brakes are applied when the accelerator pedal of a motor vehicle is trodden with a treading force/displacement not smaller than a predetermined value.
In a motor vehicle, the brakes are conventionally applied with, the use of the brake pedal and the parking brake independently the accelerator pedal. In case of an emergency, accidents often occur due to erroneous treading of the accelerator pedal instead of the brake pedal or due to the fact that the motor vehicle still travels without braking before the driver changes the pedal to be trodden from the accelerator pedal to the brake pedal and the driver actually treads the brake pedal. To avoid such accidents, there have been proposed a number of inventions relating to a pedal structure arranged such that one pedal serves as both accelerator pedal and brake pedal as disclosed by, for example, Japanese Patent Laid-Open Publications SHO49-16127 and SHO49-61826, Japanese Utility Model Laid-Open Publications SHO56-64826, SHO57-48131 and SHO59-72130. These inventions have been proposed with the object of achieving both accelerator and brake functions by treading the same pedal, not only in case of emergency, but also under normal conditions. These structures are arranged such that the accelerator and brake functions are respectively selected according to different positions at which the driver applies a treading force to the same pedal. However, it is not always easy for the driver to select either function by properly treading the same pedal. Accordingly, these inventions may not duly constitute a solution for avoiding the danger that the driver erroneously treads the pedal when applying the brakes in case of emergency.
Japanese Patent Laid-Open Publication SHO54-155529 discloses an apparatus in which the accelerator pedal treading force and treading speed are detected, and in which, if the pedal is once trodden with a treading force or a treading speed equal to or greater than a predetermined value, the engine throttle valve is thereafter closed in a continuous manner to apply the brakes, causing the motor vehicle to be rapidly stopped. Further, Japanese Utility Model Laid-Open Publication SHO61-47762 of the same applicant, discloses an apparatus in which the engine accelerator is continuously stopped upon detection of an accelerator pedal speed or acceleration speed equal to or greater than a predetermined value, and in which, upon detection of a treading displacement equal to or greater than a predetermined value, the brakes are continuously applied to emergently stop the motor vehicle.
According to these inventions, after the accelerator pedal treading force, displacement, speed, acceleration speed or the like has reached a predetermined value, the state where engine acceleration is stopped, is maintained to apply the brakes even though the factor above-mentioned thereafter becomes below the predetermined value concerned. Such application of the brakes is continued until a specified release operation is carried out, for example, by turning OFF the ignition switch (Japanese Patent Laid-Open Publication SHO54-155529), or by once releasing the accelerator pedal and treading it again (Japanese Utility Model Publication SHO61-47762). According to these inventions, the motor vehicle may be automatically stopped even though, after the driver has carried out an emergency operation when it is required to rapidly stop the motor vehicle, he falls, due to an accident or the like, into the state where he cannot futher operate the motor vehicle. This enables the motor vehicle to be securely stopped in case of emergency. However, this apparatus also involve the likelihood that, when the accelerator pedal is suddenly strongly or deeply trodden with the intention of, for example, rapid acceleration at the time it is not required to stop the motor vehicle, the emergency brakes are applied to provoke an accident.
Japanese Utility Model SHO61-47762 discloses, as an embodiment of the invention, a mechanism incorporating a spring adapted to start compression at a position slightly higher than the accelerator pedal displacement position at which the emergency brakes are applied. By such provision, the driver may become aware of the emergency braking start position. However, it is also difficult that such provision securely prevents the driver from erroneously treading the pedal.
In view of the foregoing, the present invention has the object of providing an emergency braking apparatus for a motor vehicle which overcomes the defects of the above-mentioned conventional inventions.